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CasX Protein Works for Gene Editing in Bacterial and Human Cells
Scientists find new and smaller CRISPR gene editor: CasX [berkeley.edu]
In a mere seven years, Cas9 has shown itself to be a formidable gene editor, employed in humans, plants, animals and bacteria to quickly and accurately cut and splice DNA, transforming biology and opening new avenues for treating disease. But a new kid on the block, CasX, may give Cas9 a run for its money.
Discovered two years ago [berkeley.edu] by UC Berkeley scientists Jill Banfield and Jennifer Doudna in some of the world's smallest bacteria, the protein was similar to Cas9, but quite a bit smaller: a big advantage if you're trying to deliver a gene editor into a cell. But would it work outside its native bacteria?
According to a study published today in Nature [nature.com] [DOI: 10.1038/s41586-019-0908-x] [DX [doi.org]], CasX is, in fact, a potent and efficient gene editor in both bacteria and human cells. Its design is similar to Cas9 and its well-studied cousin, Cas12, but it is different enough that it appears to have evolved in bacteria independently of the other Cas proteins. It can cut double-stranded DNA like Cas9, can bind to DNA to regulate genes, and it can be targeted to specific DNA sequences like other Cas proteins.
Plus, because it comes from bacteria that are not found in humans — Banfield dredged them from a database of microbes found in groundwater and sediment — the human immune system should accept it more easily than Cas9. Some doctors fear that Cas9 may create an immune reaction in patients treated with CRISPR therapies.
